The optimal strategy for monitoring antiretroviral therapy (ART) in resource-limited settings (RLS) is unknown. In developed countries, routine monitoring with CD4 count and viral load (VL) testing is standard practice. In RLS, however, limitations in the availability of the technology for VL testing, and in financial resources to pay for VL testing, mean that few developing countries provide VL testing as part of the routine monitoring of patients on ART. Instead, ART is monitored primary by clinical examination with CD4 testing where available. This strategy has been endorsed by the most recent WHO guidelines for ART (WHO, 2010).